From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755007Ab1AaHk3 (ORCPT ); Mon, 31 Jan 2011 02:40:29 -0500 Received: from e6.ny.us.ibm.com ([32.97.182.146]:33757 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750978Ab1AaHk2 (ORCPT ); Mon, 31 Jan 2011 02:40:28 -0500 Date: Sun, 30 Jan 2011 23:40:24 -0800 From: "Paul E. McKenney" To: Amerigo Wang Cc: linux-kernel@vger.kernel.org, Andrew Morton , Andi Kleen , Wu Fengguang , Mel Gorman , Rik van Riel Subject: Re: [Patch] rcu: remove dead code in include/linux/pagemap.h Message-ID: <20110131074024.GB2145@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1296455224-14065-1-git-send-email-amwang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1296455224-14065-1-git-send-email-amwang@redhat.com> User-Agent: Mutt/1.5.20 (2009-06-14) X-Content-Scanned: Fidelis XPS MAILER Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 31, 2011 at 02:27:04PM +0800, Amerigo Wang wrote: > TREE_RCU depends on !PREEMPT && SMP, when !CONFIG_SMP is true, CONFIG_TREE_RCU > will be false, thus "!defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)" > is always false. The relationship between these configuration parameters has indeed changed. But I am wondering if rather than removing these, the conditions need to be updated as shown below. Thanx, Paul > Remove these dead code. > > Signed-off-by: WANG Cong > Cc: Paul E. McKenney > > --- > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > index 9c66e99..e2bbbe3 100644 > --- a/include/linux/pagemap.h > +++ b/include/linux/pagemap.h > @@ -133,23 +133,6 @@ static inline int page_cache_get_speculative(struct page *page) > { > VM_BUG_ON(in_interrupt()); > > -#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU) #if !defined(CONFIG_SMP) && defined(CONFIG_TREE_PREEMPT_RCU) /* Must have CONFIG_PREEMPT here, implied by CONFIG_TREE_PREEMPT_RCU. */ > -# ifdef CONFIG_PREEMPT VM_BUG_ON(!in_atomic()); > -# endif /* * Preempt must be disabled here - we rely on rcu_read_lock doing * this for us. * * Pagecache won't be truncated from interrupt context, so if we have * found a page in the radix tree here, we have pinned its refcount by * disabling preempt, and hence no need for the "speculative get" that * SMP requires. */ VM_BUG_ON(page_count(page) == 0); atomic_inc(&page->_count); #else if (unlikely(!get_page_unless_zero(page))) { /* * Either the page has been freed, or will be freed. > @@ -158,7 +141,6 @@ static inline int page_cache_get_speculative(struct page *page) */ return 0; } #endif > VM_BUG_ON(PageTail(page)); > > return 1; > @@ -171,17 +153,9 @@ static inline int page_cache_add_speculative(struct page *page, int count) > { > VM_BUG_ON(in_interrupt()); > > -#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU) > -# ifdef CONFIG_PREEMPT > - VM_BUG_ON(!in_atomic()); > -# endif > - VM_BUG_ON(page_count(page) == 0); > - atomic_add(count, &page->_count); > - > -#else > if (unlikely(!atomic_add_unless(&page->_count, count, 0))) > return 0; > -#endif > + > VM_BUG_ON(PageCompound(page) && page != compound_head(page)); > > return 1; > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/